floating disc that floats too much!

[geomac]

I have a 88 750 Paso and since I got it in 1998 it has had full floating front discs. I guess that was the replacement for the previous owner when an original disc warped. Though now in 2012 the discs are still well within their wear limits, the discs themselves rattle as loud as an open dry clutch. I took them off and checked and it almost entirely side to side rattle. The buttons that go between the carrier and disc look fine. Soooo... after much procrastination I decided to see what could be done. The discs don't really need replacing, just.... re-shimming. I went to the McMaster-Carr website and found what I needed. mcmaster.com

98089A305 Metric 18-8 Stainless Steel Shim, 0.3mm thick, 14mm ID, 20mm OD, pack of 25 (need 24)

98317A231 Side Mount External Retaining Ring (E-style) Stainless Steel, for 10-14 Shaft Diameter, 3 packs of 10 (need 24)

About $25USD

I removed the front wheel, removed the discs from the wheel. It was very easy to remove the old clips that hold the disc on. I used the old shim and added the new shim to take up some of the slop. I could not find a proper clearance spec so I guessed at about .008 inch. The old clips had relaxed from the heat of the disc and the new ones fit much better. Anyway, I post this for any out there that may want to do the same. The test drive afterwards was much quieter, yet the discs still have plenty of play to float and align. And braking has not changed, still very good.

There are button kits available online if your look hard. But, if I remember correctly, the kits were over $80 or $90 per disc.

Your results may vary, but it worked for me.

[randtcastell]

Great info. Thanks! I have full floaters as well on front and rear.

[ducinthebay]

The difference between noise and music can sometimes be a fine line. Just ask any parent of a teenager.

Some of the floaters had really light wavy washers on them to take up slack and reduce the rattle. In fact, the current discs on most bikes are floaters, but the springy wavy washers are so strong, you don't get any rattle at all. Some have done the opposite and removed the spring washers get their stock rotors to rattle. Brembo does make a replacement button kit if you are so inclined to drill out your stock buttons.

A friend just showed me his cast iron Brembo rotors with over 100k mi. on them and they looked great. Yes, they rattle like hell, but perform great.

Cheers, Phil

[paso750]

how much the brakes rattle and move also depends on if they are full or semi floating.

G.